An air temperature threshold is a powerful indicator for anticipating potentially hazardous landslides during the spring snowmelt season, according to the results of a recent study by the U.S. Geological Survey.
"The data indicate that a high percentage of snowmelt-season landslides, in mountainous areas similar to those of the study, occur in a narrow, two-week time window after the arrival of an air temperature threshold of 58°F," said Alan Chleborad, research geologist with the USGS in Golden. Landslides, such as debris flows and debris avalanches that occurred in mountainous areas of Colorado, Utah, Wyoming, and Nevada were included in the study.
The 58°F Fahrenheit threshold identified in the study is a six-day moving average of daily maximum temperature. Analyses of the data indicate the threshold can be useful for issuing warnings of an increased potential for landslide activity in areas susceptible to snowmelt season landslides. Other potential uses include the timing of observations and deployment of field instrumentation to monitor hazardous landslide sites, timing mitigation efforts, and anticipating highway maintenance needs.
Chleborad's report entitled, "Use of Air Temperature Data to Anticipate the Onset of Snowmelt-Season Landslides," USGS open-file number 98-124, may be obtained by contacting the USGS Branch of Information Services at 303-202-4700. It is available on the internet at: http://geohazards.cr.usgs.gov
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